Hello Chris OK on the windload, the mast and rotator can handle
the forces head on to the wind at 160kph, there is data on the
RFHAMDESIGN site for the dish that agrees closely with an old
graph that I have from JPL.
I was also (mainly) considering the effects on the 4m antenna
from a performance perspective. I will put the 4m antenna 1/2
stacking distance above the dish, I think that will be the best
until I get a 3rd tropo mast. I thought perhaps that having the
dish orthogonal to the plane of the yagi elements would be better.
Anyway I'm only messing about in the UKAC on 4m, 23cms is an
altogether more serious matter.
On 19/10/2016 20:51, Christopher
What no one has any
experience or comments on this?
I find that surprising.
It has been over 6 hrs since I posted ;-)
I suspect that's because few people in the use dishes on 1.3GHz
nowadays. That's a pity ... I'm still considering the use of a
dish for tropo. from here, basing my thoughts on the very good
results I had in the late '80's from IO70 on 1.3GHz.
I know little structural engineering, but I'm not altogether sure
that parking the dish at right-angles to the wind would give as
great a gain wrt. stresses as you might think. A deep mesh dish,
eg. f/D = 0.3 or 0.4, will still project quite a significant
profile, even edge-on, which will, in effect have around twice the
effect of a an equivalent planar structure.
My old tropo dish along with a HB 6m yagi went through the Great
Storm of 1987 sat on top of a Telomast - which was guyed - above
an old AR40 rotator. It survived without a problem, despite being
parked not so far from a right angle to the wind. The survival of
the rotator was the greatest miracle in my direct experience that
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